I am unsure what is it I'm feeling?

My ex and I recently broke up because I found out that he has been sleeping with another girl for the past 6 months and to top it off he had the nerve to claim that he loved us both and wasn't sure whom he shall pick... (like picking me was ever an option anymore). During the relationship I did genuinely tell him that he was probably my first love and I used to miss him and when he came down I would get all excited and then tired because he would have a calming effect on me. The relationship was rocky sometimes because of his aggressive nature and excessive jealousy. Now that it has been over for the past few days and we no longer talk, yes I feel down but 80% of the time I feel really energetic and motivated. The other 10% is anger and remaining 10% is self-pity: 'how could he do this to me?' stuff. I did think of the reasons I would miss him for and it made me upset but I reverted to being happy soon after. The only weird side-effect is that my chest feels tight, like there is something heavy on my heart, but that is only a physical pain, I feel it even when I am hyper.

If someone asked me how I feel I would have no idea what to say, I feel fine but for the chest pain and random nostalgic moments which are really brief. I have been with someone previously, whom I claimed to love and when they left I just felt destroyed for months and even now after this break up, I thought about my previous ex and not the one I just left. Was this love and it turned into hate, was it lust, if so then why is there random physical pain? I have been dating him for a year.

I am just wondering if anyone experienced anything similar.
I am unsure what is it I'm feeling?
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